Snake River Spill — Transport Review

On March 24, 2008, the ISAB received an assignment from Dr. Usha Varanasi, NOAA’s Science and Research Director, to provide a scientific review of seasonal transportation benefit. Dr Varanasi requested that the ISAB address several questions (presented in the report) related to the "relative survival benefit of alternative Lower Snake River spill and transport operations." The ISAB was subsequently provided with additional questions and analyses for consideration by Ed Bowles, ODFW Fish Division Administrator and by CRITFC in an April 22, 2008 memo entitled "CRITFC Questions to the ISAB: Review of Lower Snake River Spill and Transport Operations." The questions posed by CRITFC and ODFW, also presented in the report, reiterated the need to address some NOAA questions but also expanded the potential scope of the ISAB review with other concerns. The ISAB response is framed in the context of questions that the ISAB synthesized from those posed by these three entities.

In sum, the ISAB finds that structural and operational changes to the hydrosystem in 2006 and 2007 are not yet fully reflected in the data available for review in this report. Moreover, very few data are available to assess the impact of alternative spill-transport operations on species such as sockeye, coho salmon, and Pacific lamprey. Even the more plentiful data for Snake River spring/summer Chinook and steelhead do not yield unequivocal results about seasonal variation in the effectiveness of smolt transport. Given the magnitude of uncertainty imposed by the nature and extent of available information, the ISAB continues to see merit in a strategy of "spreading the risk" to balance the possible risks against the perceived benefits of juvenile salmonid transportation.